PAPER SELECTED

Chimerism 78,XX/77,XX,RB in a bitch, revealed by chromosome and microsatellite studies

A 5-years-old mix breed bitch was subjected to cytogenetic evaluation due to infertility. Two cell lines were identified: 78,XX (96% of cells) and 77,XX (4% of cells). In the second line apart from two bi-armed X chromosomes, an additional bi-armed chromosome was present, which was poor in centromeric constitutive heterochromatin (C-band). It was assumed that this chromosome represents Robertsonian translocation (Rb), in which two medium size acrocentrics were involved. To resolve whether the studied case represented mosaicism or chimerism, a microsatellite polymorphism study was applied. Altogether nine microsatellite loci were analysed. At three loci more than two alleles were found. This indicated that the studied bitch was chimeric and it is suggested that this status was established during foetal life due to vascular anastomoses